The singularity of specific heat C_{V} of the three-dimensional Ising model is
studied based on Monte Carlo data for lattice sizes L≤1536. Fits of two data sets, one
corresponding to certain value of the Binder cumulant and the other — to the maximum
of C_{V}, provide consistent values of C_{0} in the ansatz C_{V} (L) =C_{0}+AL^{α/ν} at large
L, if α/ν = 0.196(6). However, a direct estimation from our $C^{max}_V$ data suggests that
α/ν, most probably, has a smaller value (e.g., α/ν=0.113(30)). Thus, the conventional
power-law scaling ansatz can be questioned because of this inconsistency. We have
found that the data are well described by certain logarithmic ansatz.